Some conventional optical detector packages include an integrated circuit mounted to a printed circuit board (PCB). Bond pads of the integrated circuits are coupled to traces of the PCB using bond wires. In one example of a conventional system, the integrated circuit is covered with a clear molding compound. Such conventional chip packages may be relatively inexpensive and applicable to a variety of different applications. However one disadvantage of such a chip package is that the over molding compound may have a temperature limitation of about 105° C. Specifically, the over molding compound may have a high coefficient of thermal expansion and may shear the bond wires if exposed to high temperatures. The over molding compound may also change optical transmission properties if exposed to high temperatures.
In another example, a conventional optical detector chip package includes an integrated circuit mounted to a PCB within a recess of the PCB. Once again, bond pads of the integrated circuit are coupled to traces of the PCB using bond wires. A glass lid is placed over the top of the integrated circuit and the bond wires with enough headroom to clear the bond wires. The glass lid may be bonded to the PCB using a conventional adhesive.
One disadvantage of such conventional example is that the amount of space between the top of the integrated circuit and the top of the glass lid may be large enough to cause noticeable diffraction. This may be due to not only the thickness of the glass lid, but also the headroom to accommodate the bond wires. Diffraction is a known phenomenon and may not be disadvantageous in some applications, but other applications may use higher precision measurements and may benefit from lower diffraction. Another potential disadvantage of some conventional chip packages is that the adhesive between the glass lid and the PCB may have a temperature limitation of about 125° C., suffering loss of integrity after exposure to higher temperatures.
Therefore, there is a need in the art for chip packages that have a higher heat specification and may provide a thinner profile to reduce diffraction.